Visitors

The comets

Comets are the solar system's messengers: ice and dust from its outer edge, flaring into light as they approach the Sun. For most of history they were the only thing in the sky that broke the rules, and so they were read as signs that the rules of life were about to break too.

What a comet is

• Nucleus: a dark lump of ice, rock and organic compounds, usually a few kilometers wide.
• Coma: a glowing cloud of gas and dust that forms as the Sun heats the nucleus.
• Two tails: a straight, bluish ion tail pushed by the solar wind, always pointing away from the Sun, and a curved, yellowish dust tail trailing along the orbit.
• Origins: short-period comets (under 200 years) come mostly from the Kuiper Belt beyond Neptune. Long-period comets fall inward from the Oort Cloud, a vast shell of icy bodies up to a light-year or more from the Sun.
• Meteor showers: the dust a comet leaves behind becomes the meteor showers Earth passes through each year.

Comets in history and astrology

• The word disaster comes from dis-astro, an ill-starred event. Comets were the classic example.
• Aristotle thought comets were fires in the upper atmosphere. Tycho Brahe proved in 1577 that they lie far beyond the Moon.
• Caesar's comet (44 BCE): appeared months after Julius Caesar's assassination and was hailed as his soul rising to the gods.
• Traditional readings: the death of rulers, war, plague, famine, and the fall of kingdoms. The color, the sign it appeared in, and the direction of the tail were all interpreted.
• Modern readings: awakening, disruption, revelation, and the arrival of something that was always coming but could not be seen until it was close.

1P/Halley

• The comet that proved comets return. Edmond Halley calculated in 1705 that the comets of 1531, 1607 and 1682 were one object and predicted its return for 1758. It arrived on schedule after his death.
• Recorded appearances: Chinese astronomers recorded it by 240 BCE. It appeared in 12 BCE, near the traditional era of the Nativity. In 1066 it blazed before the Norman conquest of England and was stitched into the Bayeux Tapestry. Giotto likely painted it as the star in his Adoration of the Magi (about 1305).
• Mark Twain was born during its 1835 return and predicted he would die with it; he died in April 1910, one day after its perihelion.
• 1910: Earth passed through its tail, triggering panic and the sale of fake "comet pills."
• 1986: met by a fleet of spacecraft, including Europe's Giotto, which photographed a dark, peanut-shaped nucleus about 15 km long.
• Orbit: about 76 years, moving opposite to the planets. It reached its farthest point in late 2023 and returns to the Sun in July 2061.
• Its dust creates the Eta Aquariid meteors in May and the Orionids in October.
• Astrological themes: generational thresholds, fate that recurs, the return of what was predicted. People born near its visits (1910, 1986) are sometimes read as generational bridge-bearers.

67P/Churyumov-Gerasimenko

• Found in 1969 by Klim Churyumov on a photographic plate taken by Svetlana Gerasimenko.
• Rosetta: the European Space Agency's probe, launched in 2004, reached the comet in August 2014 after a ten-year chase. It was the first spacecraft to orbit a comet.
• Philae: the lander touched down in November 2014, bounced twice, and came to rest in shadow. It worked for about 60 hours, briefly woke in 2015, then fell silent. Rosetta ended its mission by descending onto the comet in September 2016.
• Shape: two lobes joined by a neck, like a rubber duck, about 4 km across.
• Discoveries: organic molecules including the amino acid glycine, fueling the idea that comets delivered life's ingredients to Earth. Its water turned out to differ chemically from Earth's oceans.
• Orbit: about 6.4 years, belonging to the Jupiter family of comets.
• Astrological themes: first contact, patient pursuit, landing on the unknown, the origins of life, communication across impossible distance.

NEOWISE (C/2020 F3)

• Found in March 2020 by NASA's NEOWISE space telescope, as the world entered pandemic lockdown.
• July 2020: after surviving its pass by the Sun, it became the brightest comet seen from the Northern Hemisphere since Hale-Bopp, visible to the naked eye with a long, curved tail.
• Orbit: thousands of years. Its last visit was roughly 4,500 years ago; its next is about 6,700 years away.
• Astrological themes: beauty in isolation, a rare gift in a dark season, the reminder of scale and time. For anyone born in mid-2020, it is part of the birth sky.

Hale-Bopp (C/1995 O1)

• Found on the same night in July 1995 by Alan Hale in New Mexico and Thomas Bopp in Arizona, independently.
• Enormous nucleus: estimated around 40 to 60 km, several times larger than Halley's.
• 1997: it reached the Sun on April 1 and stayed visible to the naked eye for about 18 months, a record. It was one of the most-viewed comets in history.
• Heaven's Gate: in March 1997, 39 members of the Heaven's Gate group died by suicide in California, believing a spacecraft was following the comet to collect their souls.
• Orbit: about 2,500 years going forward; its previous visit was over 4,000 years ago.
• Astrological themes: collective awe and mass belief, spectacle, the power of a shared sign, and the danger of projecting salvation onto the sky.

West (C/1975 V1-A)

• Found in November 1975 by Richard West at the European Southern Observatory.
• 1976: after its pass by the Sun in late February, it became one of the most brilliant comets of the century, with a broad, fanned dust tail. Its nucleus then broke into four pieces.
• Orbit: hundreds of thousands of years, and its fragments may never return intact.
• Astrological themes: brilliance under pressure, breaking apart as a form of release, the moment something shatters into several paths.

'Oumuamua and the interstellar messengers

'Oumuamua was the first object ever confirmed to come from another star system. It crossed ours once, on a path that can never bring it back.

The discovery

• October 19, 2017: astronomer Robert Weryk spotted it with the Pan-STARRS telescope on Haleakalā, Maui.
• Already leaving: it had made its closest pass to the Sun in September 2017, inside Mercury's orbit, before anyone saw it.
• The name: Hawaiian, roughly "a scout" or "a messenger from afar arriving first." It is the first object given the "I" (interstellar) designation.
• Speed and path: its orbit is hyperbolic, not closed, and it arrived moving about 26 km per second relative to the Sun before the solar system ever pulled on it. It approached from the direction of the constellation Lyra, near the star Vega.

Why it puzzled scientists

• Shape: its brightness changed dramatically as it tumbled, suggesting an extremely elongated or flattened body, perhaps a few hundred meters long.
• Color: reddish, like surfaces aged by cosmic radiation.
• No visible tail: it looked like an asteroid, yet it accelerated slightly away from the Sun as comets do when gas escapes.
• Explanations proposed: hidden outgassing of hydrogen or other gases, a shard of nitrogen ice from a Pluto-like world, or, in Harvard astronomer Avi Loeb's controversial suggestion, an artificial light sail. Most scientists favor a natural explanation; the debate made it one of the most talked-about objects of the decade.

The interstellar visitors so far

Astrological meaning

• The stranger: something from entirely outside the system of the familiar. Not a return, not a cycle, but an arrival.
• The unprecedented: the first of its kind; events, people and ideas with no precedent.
• The messenger: its name makes it a herald, the first sign of something larger arriving later.
• The one-time visitor: meetings that happen once and change everything; encounters that cannot be repeated.
• Alien contact, literal and symbolic: foreign cultures, radical ideas, the parts of yourself that feel as if they came from somewhere else.
• Timing: its discovery in late 2017 is read by some as marking an era when humanity's sense of its place in the galaxy began to widen. For natal work, it matters most for people born in the few months when it was near.